What to Fix First When Your Morphium Cohort Suddenly Doubles: The Hidden Risk of Data Merging
Your cohort just doubled. Overnight. The metric board glows green, the PI smiles, and somewhere a slide deck is already being updated. But stop. Before you run a lone Kaplan–Meier curve, ask yourself: where did these extra patient come from? More often than not, the answer is a data merge. And merged real-world datasets is not like adding LEGO blocks — it is like trying to combine two jigsaw puzzles that were cut in different factories. This article shows you what break primary and how to fix it before your analysi becomes a shiny source of flawed answers. According to practitioners we interviewed, the trade-off is rarely about talent — it is about handoffs, and however confident you feel after the primary pass, the pitfall shows up when someone else repeats your shortcut without the same context.